A number of reasons. Politics is playing a big part. France is in election season. The opposition parties have pledged to deal with the Jungle problem. That has prompted President Francois Hollande, who is not doing well in the polls, to do the same.

On a humanitarian level though, pretty much everyone agrees that the Jungle shouldn't exist and needs to be cleared. The question is how and when.

French riot police have clashed with migrants just hours before the planned clearance of the 'jungle' refugee camp in Calais is due to start

Clashes and fires are not unusual at the camp, but tensions on Sunday night were particularly high

A migrant is surrounded by tear gas as he throws stones at French riot police

A portable chemical toilet is ablaze

At least 6,500 refugees and migrants are estimated to be living in the 'jungle'

French authorities will begin evacuating the camp later on Monday

It is due to have been completely demolished by the end of the week

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Charities are extremely concerned that there are vulnerable families and unaccompanied minors in the camp. They have repeatedly told the authorities that provisions need to be made for them.

In July the charity Citizens UK gave the UK government a list of 178 minors all of whom claimed to have family in the UK. Under European law they are entitled to be with their family.

In August the names of a further 212 minors were passed to the British authorities. Under an amendment to the UK immigration act, they too were eligible to come to the UK, but the authorities didn't act.

: How many people live there?

Local charities have estimated there are more than 10,000 people living in the Jungle. That figure is based on an unofficial census carried out in September.

However, other charities and the local government believe the accurate figure is more like 6,000. This is still a huge number of people living in a very cramped space.

:: What about children? Are there really young children living in the camp?

There are hundreds of young people living in the camp - I have seen them on every one of my many visits.

However, establishing how many of them are under 18 (minors) and how many are unaccompanied is hard. It's in the migrants' interests to lie about their age in order to increase their chances of getting to the UK.

That's not to say that they all lie about their age. Many don't need to - I have seen plenty of teenagers who look very young and I have met younger children too. But the issue is complicated further because press regulations prevent us from photographing minors without parents' consent. If they are unaccompanied, that's hard.

A census by the French charity Terre d'Asile earlier this month estimated that there were 1,290 unaccompanied minors in the camp. Since then, the UK has accepted more than 200 of them.

Charities are worried that those who remain in the camp may go missing as demolition begins.

:: Wasn't the Jungle already demolished earlier this year?

Not quite.

The southern half of the Jungle was demolished at the end of February. The hope then was that those who lived in the southern half would either head to official camps elsewhere in France. Some did, but many others didn't, and moved instead to the northern half of the camp.

The consequence was that the Jungle halved in size geographically but by the summer it was larger in population than it had ever been.

Most of those who live in the Jungle are African and many can be classed as economic migrants. In other words, they are not fleeing war but leaving their impoverished homes for a better, more prosperous life. They are unlikely to get asylum in Europe and, if the system was working properly, they would be deported.

This is by no means the case for all the Jungle inhabitants though: Eritreans are fleeing a dictatorial regime and compulsory conscription, South Sudanese are fleeing a fierce civil war, Ethiopians are fleeing growing levels of political oppression and violence.

And for all of them, the draw to a better life in Europe is so strong, that they're crossing desert and sea to begin new lives.

The authorities have spent the weekend handing out leaflets to the Jungle inhabitants in numerous languages explaining what will happen over the coming days.

The migrants are being asked to assemble at a 3,000 square-metre warehouse just outside the Jungle site. The warehouse will be open from 8am to 8pm on Monday, Tuesday and Wednesday this week.

Inside, the migrants will be divided into four different groups: ordinary migrants, migrants claiming to be unaccompanied minors, families and vulnerable people.

The migrants will give their name, date of birth and nationality. In theory, as the Jungle population moves out, it will be dismantled.

:: Where will the people move?

A total of 167 new asylum centres have been established around France with room for 7,500 people.

In the warehouse, the migrants will be designated an asylum centre and receive a corresponding coloured bracelet. Buses will then transport the migrants to the centres. Sixty buses have been chartered for Monday, 45 for Tuesday and 40 for Wednesday. Each bus can carry 50 people.

At the centres, people will be able to claim asylum in France.

The unaccompanied children will remain in Calais inside purpose built container cabins on the Jungle site. They will then be assessed for eligibility to come to the UK.

:: Will this solve the problem?

No. Migrants will keep coming.

Thousands are rescued weekly in the Mediterranean and brought to Italy. They can't be taken back to Libya (their African departure country) because it's in a state of war. They are brought to camps in Italy but simply walk out. New camps are already popping up in the countryside around Calais.